It is a common thing to walk across to a shop on a bright sunny day. One thing which affects us on such an instant is the glare. Now, how is this glare caused? When sunlight hits flat surface of the road or water or the hood of cars they become concentrated and this concentrated light is called polarized light. It is reflected back in all directions (i.e.) horizontally and vertically; it is the horizontal reflection which causes the glare.
The advantage of POLARIZED lenses is that they absorb all the bright horizontally reflected light waves and allow only the vertical light rays without the brightness to pass through the glasses. Thus they protect the eyes from harmful UV radiation and glare. That is why eye doctors prescribe Polaroid lenses for their patients. They help to reduce the incidence of cataracts in people. It is good to be used by people who have undergone a cataract surgery as they are advised by doctors not to see bright light.
These glasses do not make the whole field of vision dimmer, rather they selectively block out the glare. They help the wearer to see without eye strain and make the viewing experience more comfortable.
It is advisable to wear a polarized pair of glasses when you are driving on a hot sunny day as it reduces the effects of mirage. It helps the driver to see more clearly and react quickly to oncoming traffic. So it can save people from potential hazards. It cuts out the reflection of charts or other things which may cast their reflection on the windscreen.
Polarized lenses have a film sandwiched between two other layers of the lens or attached to the front of the lens. Ordinary sunglasses do not have this special layer. So they do not block glare. They cause distortions in the color of the objects seen or viewed. On the other hand polarized lenses reduce eye fatigue and provide for clear contrasts.
We can find out if a particular pair of glasses is polarized or not. For this we have to tilt the glasses and rotate them. Non polarized lenses will allow vision at all times but the polarized lenses will become dark and not allow vision when they are held vertically.
Generally polarized lenses cost more than their ordinary counterparts. However the extra amount we pay is for the quality. They reduce eye fatigue and give a crystal clear vision. They are good for long distance driving and sports like cycling. They are best for fishing because they allow the fishermen to see what lies in the depth of the river or stream by cutting out the glare. They are a security product in case of sailing as obvious as a life jacket.